Draconigena Says:

After 2 weeks of collecting for Raiding with leashes 3, I am at 9/12 (using 2 characters, and having traded 1 pet) so pretty comfortable going on.

Coilfang stalker refused to drop for over a year (honestly, blizzard, you should add a failsafe mechanism for this kind of things), and since the price gone down so much, I have stopped trying a few weeks ago.

At the moment I am trying to get a second Pandaren water spirit and a second Chrominius for the howl bomb tactic.